The present invention relates to a camshaft phaser for controlling the phase relationship between the crankshaft and a camshaft of an internal combustion engine; more particularly, to a phaser having a central attachment bolt and an oil control valve mounted in the phaser front cover; and most particularly, to a central attachment bolt element having a first passage for flow of oil from a camshaft bearing to the control valve, and having second and third passages for flow of oil from the control valve to advance and retard chambers in the phaser.
Cam phasers for varying the phase relationship between the pistons and the valves of an internal combustion engine are well known. In some applications, pressurized phaser control oil must be supplied from a passage in a camshaft bearing at the rear of the phaser to a fixed oil control valve mounted on the engine block at the rear of the phaser. The oil control valve, on command from an engine control module, supplies oil to, or recovers oil from, opposite-acting timing advance and retard chambers within the phaser.
Such a known mounting can require significant modification to the camshaft bearing mount and engine block, a disadvantage in adapting a phaser to an engine design already in production. In an improved configuration, the oil control valve may be mounted in the outer cover at the front of the phaser; however, a problem then arises as to means for providing oil from the camshaft bearing to the oil control valve, and from the oil control valve to the advance and retard chambers.
What is needed is a means for providing oil from the camshaft bearing to the oil control valve of a camshaft phaser mounted in the phaser cover, and for distributing oil from the oil control valve to the advance and retard chambers of the phaser.
It is a principal object of the present invention to provide an improved camshaft phaser requiring minimal engine alteration for installation thereupon.
It is a further object of the present invention to reduce the cost and complexity of manufacturing an internal combustion engine equipped with a camshaft phaser.
It is a still further object of the invention to reduce the cost and complexity of a camshaft phaser having an oil control valve disposed in the phaser cover.
Briefly described, a central bolt for attaching a camshaft phaser to a camshaft of an internal combustion engine is provided with a first longitudinal passage for supplying engine oil under pressure from a front camshaft bearing to an oil control valve disposed in an outer cover of the phaser and with second and third longitudinal passages for supplying phaser control oil from the oil control valve to advance and retard chambers, respectively, within the phaser.